There are coffee machines in which portion packs can be introduced into a holder, which can then be inserted into a closeable housing for a brewing operation. If a relatively large quantity of coffee is to be brewed, it is possible to insert another holder in order for two portion packs to be introduced. The disadvantage with this brewing apparatus is that different holders have to be used for different quantities of coffee or portion packs. This, on the one hand, involves laborious handling and, on the other hand, is inflexible since, depending on taste, finer apportioning of the quantity of coffee is desirable.